<html>
<head>
  <style>
    #outer {
      position: absolute;
      top: 0px;
      left: -1000px;
      height: 300px;
      width: 300px;
      z-index: 1;
      overflow: auto;
      background-color: green;
    }

    #inner {
      will-change: transform;
      background-color: blue;
    }

    #overlap {
      width: 500px;
      height: 500px;
      background-color: yellow;
      will-change: transform;
    }
  </style>
  <script type="text/javascript">
    if (window.testRunner) {
      testRunner.waitUntilDone();
    }

    function doTest()
    {
      if (window.internals) {
        internals.forceCompositingUpdate(document);
      }
      // Move green div so that it overlaps the yellow div, and hence
      // needs its own backing.
      document.getElementById("outer").style.left = "0px";
      if (window.testRunner) {
        testRunner.notifyDone();
      }
    }

    window.addEventListener('load', doTest, false);
  </script>
</head>

<body>
  <div id="outer">
    <div id="inner"></div>
  </div>
  <div id="overlap"></div>
</body>
</html>
